An Organic Light-Emitting Diode (OLED) is a display lighting technology that has been developed in recent years. Especially in the display industry, it is one of the hotspots in the field of flat panel display research. Compared with a liquid crystal display, it has advantages such as high response, high contrast, flexibility, low power consumption, low production cost, self-illumination, wide viewing angle and fast response. At the present, in the display field, such as in mobile phones, PDAs, digital cameras and the like, the OLEDs have begun to replace traditional LCD screens. It is considered to have broad application prospects and important research significance. In particular, top-emitting OLED devices are being studied actively due to their advantages such as higher aperture ratio and light extraction optimization using micro-cavity.
Unlike TFT-LCDs, which use a stable voltage to control brightness, the OLEDs are current-driven and require a stable current to control illumination. The OLEDs are typically made of low-temperature poly-silicon (LTPS). When the OLEDS are used in medium and large-sized high-PPI panels, the load of a small-sized panel will be increased manyfold, and as the pitch between pixels becomes smaller, part of the storage capacitance (Cst) will be sacrificed, which will greatly degrade the display performance.
In the medium-sized high-PPI panel design, a small-sized and low-resolution panel has a large RC load (and therefore a large resistive voltage drop), which will cause a serious IR voltage drop of VDD (that is, power line of a thin-film transistor) and Vdata (that is, a display data line or display signal line) in the LTPS OLED process, resulting in greatly degrading the panel display performance. At the same time, in high-PPI panels, the pixel size is getting smaller and smaller, the width of the signal line is larger due to the limiting by the process conditions, and thus part of the Cst is sacrificed to ensure the arrangement of the pixel circuit structure. In order to reduce the resistance load and increase the Cst, it is necessary to make change using methods such as increasing masks or changing material and so on, which will greatly increase process steps and product costs.
Therefore, the technical problem that needs to be solved urgently is to design a new pixel circuit structure and a display device using the same.
The above information partly disclosed in this background section is only for enhancement of understanding of the background of the present disclosure, and thus it may include information that does not constitute the prior art known to those ordinary skilled in the art.